Diffuser



Dec. 13, 1966 e. c. SYLVESTER ET AL 3,291,028

DIFFUSER Filed March 31, 1964 60 55 Fla 2 Fm?) 70 4mm lNVENTO S GORDON C.SYLVES R JOHN F. Newau.

United States Patent 3,291,028 DIFFUSER Gordon C. Sylvester and John F. Nowell, Verona, Wis., assignors, by mesne assignments, to Wehr Corporation, Milwaukee, Wis, a corporation of Wisconsin Filed Mar. 31, 1964, Ser. No. 356,240 7 Claims. (Cl. 98-4tl) This invention relates to diffusers and, more particularly, to diffusers of the type adapted for use in systems handling adjacent, oppositely flowing streams of air or other gaseous media.

For example, in an air conditioning system of this type cool primary supply air is transported in a passage immediately adjacent a return air passage which is carrying relatively warmer air from the room, or the like, being supplied. The primary and return air passages are separated by a common duct member and the diffuser provided at the opening of the return and supply air passages to the room normally includes a partition forming an ex tension of the common duct member and also serving to separate the diffuser into return and supply portions. It has been observed that the primary supply air effects a cooling of the partition so that as the moisture carrying relatively warmer return air from the room engages the cool partition moisture condenses on the partition. A solution which has been proposed for this problem of moisture condensation is to provide thermal insulation for the partition so that the return air will not be subject to such .a marked differential in temperature. However, this proposal is not completely satisfactory as it requires additional material and complicates both the construction and assembly of the diffuser.

The object of this invention is to provide an improved and simplified solution to this problem of moisture condensation in systems of this type.

For the achievement of this and other objects, this invention proposes to effect a partial mixing of the return and supply air at the diffuser. The mixing is preferably accomplished in the area of the juncture between the return and supply air portions of the diffuser and a portion of the mixed air is entrained with the return air stream to flow along the return air side of the diffuser partition and common duct member. The temperature of the layer of mixed air flowing along the return side of the partition will be between that of the return and supply air and sufficient mixing is achieved so that the dew point temperature of the mixed air is below the surface temperature on the return side of the partition to thereby preclude condensation as the mixed air contacts the relatively cool partition.

The novel features of this invention are set forth in the appended claims. The invention itself, together with additional objects and advantages thereof, will be more clearly understood from a reading of the following description in connection with the accompanying drawings wherein a preferred embodiment of the invention is illustrated and in which:

FIG. 1 is a plan view of a diffuser mounted in a ceiling and viewed from below the diffuser;

FIG. 2 is a partial section view taken along lines 22 of FIG. 1; and

FIG. 3 is a partial section view taken along lines 3-3 of FIG. 1.

This invention is illustrated and will be described as incorporated in an air conditioning system which includes two relatively spaced rectangular duct members and 12 extending in coaxial relationship. The construction and function of a duct arrangement of this type is well known in the art and for that reason will not be specifically described in this application. Briefly, duct member 10 forms an inner return air passage 14 and, in cooperation with outer duct member 12, defines an annular supply air passage 16 surrounding the inner passage. As illustrated by the arrows in FIG. 3, cool primary supply air is discharged through passage 16 on one side of common duct member 10, whereas, relatively warmer room air is drawn into return air passage 14 on the opposite side of the common duct member.

In accordance with common practice, a diffuser is associated with the return and supply air passages, i.e. at the point where air is discharged to and withdrawn from the room. The diffuser includes a generally planar, rectangular return air grille 1-8 and a generally annular supply air grille assembly 20 arranged in surrounding relationship with return air grille 18. The supply air grille is made up of a plurality of louvers 22 supported by frame member 24 in a manner described and claimed in the co-pending application of John F. Newell and Robert O. Barnes entitled Louver Mounting, Serial No. 311,367, filed Sept. 25, 1963, and assigned to the assignee of this application. As disclosed more completely in that application, each of the louvers includes a formed end 26 which fits into and is locked in place by conforming notches 27 in frame member 24.

Frame member 24 is connected to the outermost louver 28 of the grille by a plurality of relatively spaced bracket assemblies 30. Each bracket assembly 30 includes an L-shaped bracket 32 attached to frame member 24 by rivets 34 and connected to louver 28 through bracket 36 which is in turn connected to the louver by rivet 38. The connection between brackets 32 and 36- can be made in any suitable, well-known manner, for example, by using a U-shaped clip no to receive a portion of bracket 36 and to anchor screw 42 to complete the connection. This type of connection being well known in the art and forming no part of this invention is not specifically illustrated in the drawings. Outer louver 28 can be suitably connected (connection not shown) to the ceiling 44 or to duct member 12 so that the supply air grille assembly registers with and provides a terminal portion for primary supply pir passage 16-.

The return grille is connected to duct member 10 through frame assembly 46 which also establishes a connection between the supply air grille and the return air grille in such a manner that, while the primary supply air grille registers with the supply air passage, the return air grille registers with return air passage 14. More particularly, frame assembly 46 includes partition 48 which is generally L-shaped in cross section and includes first portion 5% arrange-d for engagement with duct member 10*. Portion 50 extends coextensively with duct member 19 and is disposed generally parallel to the direction of return air flow to provide an extension of return air passage 14. Partition 48 also includes a second portion 52 extending generally transversely of first partition portion 50, and, correspondingly, transversely of the return and primary air flow. It should also be noted that partition 48 engages an end of frame member 24 and that the second partition portion 52 forms a horizontal shelf to support the frame members.

Frame assembly 46 also includes a rectangular, or gen erally annular, return grille frame 54 engaging the periphery of and supporting the return grille. Specifically, return grille frame 54 includes a generally horizontal member 56 disposed transversely of the direction of air flow to divert a portion of the return air flow in a manner and for a purpose to be described more completely hereinafter. A vertical member 58 extends from the inner side of member 56 and is spaced inwardly of the inner edge of member 56 to form a supporting shelf for return grille 18. A channel-shaped groove 60 is also provided on the inner side of transverse number 56 for receipt of L-shaped bracket member 62. Bracket member 62 connects the return grille frame to partition member 48 and includes a leg 64 terminating in transverse bar 66 engaged in channel 60 and leg 68 which extends along partition portion 52 and is connected thereto by screws 76 extending through the bracket and the partition portion and held in place by a suitable retainer 78. Transverse bar 66 is held in opening 60 by cooperation of tabs 70 and 72 and raised portion 74 which engage opposed sides of the transverse bar. It will be noted from FIG. 1 that four bracket members 62 are provided to support return grille frame 54 in the frame assembly.

With the return air grille frame being supported in spaced relationship from partition portion 52 and connected thereto only at relatively spaced points along its periphery, a substantially unobstructed opening is defined in the area of the juncture between the primary and return air streams which opening extends transversely of and provides communication between the primary and return air streams. Horizontal frame member 56 is presented to the return air flow and acts as a bafile to divert a portion of the return air into the primary air and effect a mixing of the primary and return air. With reference to FIG. 3, the full line arrows represent both the return and primary air streams and the dotted line arrows represent the mixed air entrained with the return air. Mixing of primary and return air occurs at the opening defined by the termination of partition portion 52 and the return grille frame and a portion of the mixed air is entrained with the return air supply and flows along the return air side of partition 48. This layer of mixed air will be at a temperature between the temperature of the primary supply air and that of the return room air. The opening defined by partition 48 and transverse member 56 is selected so that the amount of mixing which occurs and, correspondingly, the resulting temperature of the mixed air will be such that the dew point temperature of the mixed air is lower than the surface temperature on the return side of the partition and the common duct to thereby prevent condensation as the mixed air engages the partition and duct.

As can be seen in FIG. 3, transverse portion 52 of the partition preferably terminates in an angularly disposed end 80 so as not to interfere materially with the primary air supply. Furthermore, bracket 62 includes a stepped corner 63 which cooperates with partition end 80 to position the return grille frame relative to the partition to define the particular opening for achieving the amount of mixing desired. It will be appreciated that the mixing required and the temperature of mixed air to be achieved will vary depending upon the particular system or installation with which the diffuser is used and can be achieved by varying the opening between the partition and the return grille frame in accordance with the cfm. of air to be handled and the expected temperature differential between the supply and return air streams.

This invention provides a relatively simple diffuser construction which obviates the problem of moisture condensation in systems of the type described. It will be appreciated that, although this diffuser construction has been discussed in connection with an air conditioning system, it is not necessarily limited to such use but could be incorporated in any gaseous media supply system carrying adjacent streams which are at different temperatures and discharged and drawn into the system at the same point so as to present a condensation problem. Furthermore, although the illustrated embodiment of this invention utilizes the return grille frame as the baffle to interrupt and divert return air to effect mixing, an arrangement which is particularly desirable as it provides a very simple structure, a bafile other than the frame could be used equally as well.

Therefore, although the present invention has been illustrated and described in connection with a single em- Ibodiment thereof, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

What we claim is:

1. A diffuser for use with a system including adjacent, coaxially arranged inner and outer ducts defining adjacent passages for oppositely flowing streams, said diffuser comprising, in combination,

an inner grille,

an outer grille arranged around the periphery of said inner grille so that said inner and outer grilles are adapted to extend across and register with a respective one of the passages defined by said inner and outer ducts,

and frame means for connecting said inner and outer grilles to each other and to said ducts, said frame means including partition means arranged at the juncture between said inner and outer grilles and including a first portion extending transversely with respect to said grilles for connection with said inner duct and a second portion extending generally transversely of said first portion, said first and second portions having an extension generally coextensive with said inner duct to define an extension of said passages, inner grille frame means extending around and engaging the periphery of said inner grille and including a portion extending generally parallel to said second partition portion and directed outwardly of said passages and presented to the flow into one of said grilles, and a plurality of bracket means connected between said inner grille frame means and said second partition portion supporting said parallel extending portion in spaced relation from said second partition portion to define a restricted opening between said second partition portion and said parallel extending portion and provide communication between the flow through said inner and outer grilles, said diffuser adapted to accommodate flow on both sides of said frame means and said inner grille frame means portion diverting a portion of the flow directed through one of said grilles into the flow directed through the other of said grilles to produce a mixing of said flow in the area of said opening whereby a portion of the flow directed through the other of said grilles is entrained with the flow directed through said one grille.

2. The combination with adjacent, coaxially arranged return and supply passages adapted to accommodate oppositely flowing streams and defined by a common elongated hollow duct member and a second duct member spaced outwardly from and coaxially arranged with said common duct member, of a diffuser comprising, in combination,

first diffuser grille means,

second generally annular diffuser grille means,

means supporting said first grille means in registry with the passage defined by said common duct member and said second grille means in surrounding relation with said first grille means and in registry with the passage defined between said common duct member and said second duct member,

said support means including a frame member disposed at the juncture between said first and second grille means and having a surface directed outwardly of said duct members and presented to flow into said return passage, partition means connected to and generally coextensive with said common duct member and extending outwardly from said common duct member to define an extension of said return and supply passages, flow through said diffuser to and from said passages thereby occurring on both sides of said partition means, and means connecting said partition means and said frame member,

said partition means having -a terminal end disposed in general alignment with and spaced inwardly of said frame member to define with said frame member an opening between said return and supply passages adjacent to but spaced inwardly of the outer termination of said grille means to provide communication between the flow on opposite sides of said partition means at the entrance end of said return passage and the discharge end of said supply passage,

and said frame member diverting a portion of the return flow into the supply flow to produce a mixing thereof in the area of said opening so that a portion of said mixed flow passes through said opening and is entrained with the flow into said return passage.

3. The combination of claim 2 wherein said return passage is defined by said common duct and said supply passage extends around said return passage,

said frame member is generally annular extending substantially coextensively with the juncture between said first and second grille means,

said second grille means includes angularly disposed louvres directed outwardly of said passages and away from said return passage,

and said terminal end of said partition means comprises an angular portion extending generally parallel to said louvres.

4. The combination of claim 2 wherein said frame member engages the periphery of and supports said first grille means in said diffuser,

and said support means also includes a plurality of bracket means connected between said partition means and said frame member, said bracket means relatively spaced apart around said partition means to support said frame member from said partition means with minimum interference with the communication between said passages through said openmg.

5. The combination with adjacent return and supply passages adapted to accommodate oppositely flowing streams and having a common duct member separating said passages of, a diffuser comprising, in combination,

first and second diffuser grille means,

means supporting said first grille means in registry with said return passage and said second grille means in registry with said supply passage, partition means connected to and extending outwardly from said common duct member toward said grille means in general alignment with the juncture between said first and second grille means and defining an extension of said return and supply passages so that flow through said diffuser to and from said passages occurs on both sides of said partition means,

baffle means positioned at said juncture and presented to flow into said return passage,

said partition means terminating in general alignment with and spaced inwardly of said baffle means to define with said baffle means an opening between said return and supply passages adjacent to but spacedinwardly of the outer termination of said grille means to provide communication between the flow in said passages at the entrance end of said return passage and the discharge end of said supply passage,

and said baffle means diverting a portion of the return flow entering said diffuser into the supply fiow leaving said diffuser to produce a mixing thereof in the area of said opening so that a portion of said mixed flow passes through said opening and is entrained with said return flow.

6. The combination of claim 5 wherein said baffle means comprises a frame member providing a portion of the support for said grille means in said diffuser and wherein said partition means terminates in an end portion extending generally parallel to but spaced from said frame member to cooperate with said frame member in defining said opening through which said return passage communicates with said supply passage.

'7. The combination of a diffuser and duct means adapted to accommodate adjacent oppositely flowing air streams which are at relatively different temperatures and to deliver air at one temperature to an area to be conditioned and receive return air from said area at a different temperature, said combination comprising,

duct means defining first and second adjacent passages accommodating said oppositely flowing air streams and including common duct means separating said passages,

first means in registry with said first passage and defining an entrance end to said first passage for said return flow, sec-0nd means adjacent to said first means and in regis try with said second passage defining a discharge end from said second passage for supply air flow,

baffle means positioned between said entrance and discharge ends and presented to return flow into said first passage,

and means adjacent to said discharge and entrance ends but spaced from said discharge and entrance ends in a direction into said first and second passages and defining an opening through said common duct means to provide communication between said first and second passages inwardly of said entrance and discharge ends, flow through said adjacent passages occurring on both sides of said opening and the diversion of flow into said entrance end into the flow from said discharge end producing a mixing of said flows at said baffle means and in the area of said opening, said mixed air being at a temperature between that of said return and supply air and a portion of said mixed air passing through said opening into said first passage and along said common duct means to prevent condensation within said passages.

References Cited by the Examiner UNITED STATES PATENTS 2,199,525 5/1940 Kurth 98-40 2,616,355 11/1952 McCabe 9840 2,664,041 12/1953 Twede 984O ROBERT A. OLEARY, Primary Examiner.

JOHN F. OCONNOR, Examiner.

W. E. WAYNER, Assistant Examiner. 

7. THE COMBINATION OF A DIFFUSER AND DUCT MEANS ADAPTED TO ACCOMMODATE ADJACENT OPPOSITELY FLOWING AIR STREAMS WHICH ARE AT RELATIVELY DIFFERENT TEMPERATURES AND TO DELIVER AIR AT ONE TEMPERATURE TO AN AREA TO BE CONDITIONED AND RECEIVE RETURN AIR FROM SAID AREA AT A DIFFERENT TEMPERATURE, SAID COMBINATION COMPRISING, DUCT MEANS DEFINING FIRST AND SECOND ADJACENT PASSAGES ACCOMMODATING SAID OPPOSITELY FLOWING AIR STREAMS AND INCLUDING COMMON DUCT MEANS SEPARATING SAID PASSAGES, FIRST MEANS IN REGISTRY WITH SAID FIRST PASSAGE AND DEFINING AN ENTRANCE END TO SAID FIRST PASSAGE FOR SAID RETURN FLOW, SECOND MEANS ADJACENT TO SAID FIRST MEANS AND IN REGISTRY WITH SAID SECOND PASSAGE DEFINING A DISCHARGE END FROM SAID SECOND PASSAGE FOR SUPPLY AIR FLOW, BAFFLE MEANS POSITIONED BETWEEN SAID ENTRANCE AND DISCHARGE ENDS AND PRESENTED TO RETURN FLOW INTO SAID FIRST PASSAGE, AND MEANS ADJACENT TO SAID DISCHARGE AND ENTRANCE ENDS BUT SPACED FROM SAID DISCHARGE AND ENTRANCE ENDS IN A DIRECTION INTO SAID FIRST AND SECOND PASSAGES AND 